The Holotype is an adult female of 107mm standard length, collected by A. Dugès. He sent two specimens to the Museum on August the 24th, 1891.

Terra typica:

Tarleton Bean indicated the type location for the Holotype simply with "Mexico", but as he described several species from this fish collection of Alfredo Dugès from 1891, all of them collected in the state of Guanajuato, this was seen as a hint of a more detailed location information for the type of Alloophorusrobustus. But again, there is a sign attached on the Holotype defining its origin more precisely as "Patzcuaro, Mex.", which is a different drainage and accepted as the correct type location.

Etymology:

The name can be derived from the Latin and means "strong". Bean didn't explain why he had chosen this eptithet, but compared with other representatives of the genus Fundulus (wherein Bean placed this fish), he is stronger and bigger, so maybe this was the reason. Another, also reasonable possibility would be the strong jaws of this Goodeid - typically for this species -, that inspired Bean to this species name.

The Bulldog Splitfin belongs to a few Goodeid species with a large distribution range. It is historically known from the federal states of Guanajuato, Jalisco and Michoacán and occured at the type location, the endorheic Lago de Pátzcuaro, with surrounding springs and tributaries, the adjacent endorheic Laguna de Zirahuén including the Estanque Las Condembas (Lago de Opopeo), and the likewise endorheic Río Grande de Morelia basin with the Lago Cuitzeo, several springs of the Río Grande de Morelia, the Presa Cointzio, the Laguna de Yuriría and several affluents of the Cuitzeo lake. The historical range includes furthermore the ríos San Antonio (Río Santa Bárbara) and Cupatitzio in Uruapán, Río Balsas drainage, the Río Angulo drainage with the Lago Zacapú, and several northern tributaries of the middle Río Lerma like the ríos Laja, Turbio and Guanajuato. More collection sites are known from the Río Duero drainage (a lower Río Lerma affluent) including several spring areas (Presas Orandino and Verduzco), the Lago de Chapala with the isolated Lagos Los Negritos E of the lake and subsequent sections of the Río Grande de Santiago, and finally the Presa San Juanico and other habitats in the Río Grande (not Río Grande de Santiago!) headwaters in the Cotija region, Río Balsas drainage. Lyons (2011) reported that this species disappeared from the Lago de Chapala, the adjacent Río Grande de Santiago and the Río Lerma and most of its tributaries. It is no more inhabiting the Laguna de Yuriría and lost its last stronghold N of the Río Lerma in a spring in San Francisco del Rincón, so possibly no habitats in the states of Jalisco and Guanajuato (except for N shores of the Cuitzeo lake) have remained. It has become rare in many other habitats, larger stocks can be found only in some springs of the Río Duero drainage, the spring at the Molino Viejo de Chapultepec (Lago de Pátzcuaro drainage), the Lago Zacapú and the La Mintzita spring (Río Grande de Morelia drainage). Taking in consideration its affiliation to different separate river drainages respectively endorheic basins and phylogenetic results, ten subpopulations in two lineages can be inferred: The Lago de Pátzcuaro subpopulation (type subpopulation), the adjacent Río Grande de Morelia subpopulation (including the Lago Cuitzeo), the Río Angulo subpopulation (including the Lago Zacapú) and the possibly Extinct lagunas de Zirahuén and Yuriría and Middle Río Lerma subpopulations, the last one encompassing several rivers in Guanajuato like the ríos Turbío, Guanajuato and Laja. Representatives from these six drainages belong phylogenetically to one lineage with respect to the following four ones, which again form a distinct lineage and probably even a separate to be described species: The Río Duero subpopulation (lower Río Lerma basin), the Cotija subpopulation (upper Río Balsas drainage), the Río Cupatitzio subpopulation, also in the Río Balsas headwaters in and S of Uruapán and the Lago de Chapala-Río Grande de Santiago subpopulation, now possibly Extinct except for the isolated Lagos Los Negritos about 10km E of Sahuayo. Further studies to reveal the phylogenetic relationship within this species are required. The underlined names are the ones officially used by the Instituto Nacional de Estadística y Geografía; nevertheless, other ones might be more often in use or better known and therefore prefered.

ESU ist short for Evolutionarily Significant Unit. Each unit expresses an isolated population with different genetic characteristics within one species. ESU's can be defined by Molecular genetics, Morphology and/or Zoogeography and help in indicating different phylogenetic lineages within a species. The abbreviation for an ESU is composed of three letters of the genus, followed by the first two letters of the species name and an ongoing number in each species.

In Alloophorus robustus, actually four ESU's are distinguished. The first one (Alpro1) is in use for specimens from the Lago de Chapala and connected rivers like the lower Río Lerma, the Río Duero with the famous springs of La Luz and Orandino, the lakes of Los Negritos and watersheds southeast of Chapala like the region of Cotija, the Presa de San Juanico, the bath at Tocumbo and the spring system at Uruapán. This ESU quite sure comprises a separate to be described species.

Alpro2 encompasses populations from the Lago de Cuitzeo and Zacapu basins, Alpro3 those north of the middle Río Lerma (Río Turbio, Río Guanajuato, Río Laja). The fourth and last ESU, Alpro4, is in use for fish from the type location (Lago de Pátzcuaro) and connected waterbodies and from the Lago de Zirahuén.

Distribution of the Bulldog Splitfin. Four subsequent detailed maps, clockwise from A to D, show the populated sub- and infrabasins. In all the maps, the bold red line encompasses the species' distribution, the thin red lines separate the infrabasins, partly even ESU's. For a more detailed distribution, see the map for the Maximum Extent of Occurence (EOO):

Map A - Northern drainages: Within the Río Lerma basin, the species occupied within the Río Laja subbasin the Middle (MLA) and Lower (LLA) infrabasins, within the Middle Río Lerma basin its Upper (MLE-U) and Lower (MLE-L) sections as well as the ríos Temascatio (TEM) and Guanajuato (GTO) infrabasins. Furthermore Upper (UTU), Middle (MTU) and Lower (LTU) Río Turbio infrabasins, also Middle Río Lerma subbasin. These drainages were populated by the ESU Alpro3 and the Bulldog Splitfin is probably extinct in all of these drainages:

Map B - Eastern drainages: Additionally to already mentioned drainages, Alloophorus robustus is known from the endorheic Laguna Yuriría (YUR), Lago de Pátzcuaro (PAT) and Río Grande de Morelia/Lago Cuitzeo (CUI) infrabasins within the Río Grande de Morelia subbasin, and from the Río Angulo (ANG) infrabasin, Lower Río Lerma subbasin, all Río Lerma basin. The species still inhabits all these drainages, probably except for the Laguna Yuriría. The Laguna Yuriría was populated with fish from the ESU Alpro3, originating in the Middle Río Lerma subpopulation, the Pátzcuaro lake is home to Alpro4, the other two infrabasins are the ones where Alpro2 occurs:

Map C - Southern drainages: From the south, the Chegua is known exclusively from the Río Balsas basin: The Cotija infrabasin (COT), Upper Río Grande subbasin, and the Río Cupatitzio (CUT) and Laguna Zirahuén (ZIR) infrabasins, both Lower Río Grande subbasin. The species has probably become extirpated from the Zirahuén basin (ESU Alpro4), but persists in the other two (ESU Alpro1):

Map D - Western drainages: The species is described from the Lower Río Lerma subbasin including - besides the already mentioned Río Angulo infrabasin - the Lower Río Lerma infrabasin (LLE), the ríos Chico (CHI) and Duero (DUE) infrabasins, and the Jamay-Pajacuarán infrabasin (JPA). Within the Laguna Chapala subbasin, it is known from the Laguna Chapala infrabasin (CHA) and the Río Sahuayo infrabasin (SAH), within the Río Grande de Santiago subbasin from the Laguna Cajititlán infrabasin (CAJ), from the Zapotlán del Rey infrabasin (ZAP) and (maybe) from the Zapotlanejo infrabasin (ZJO). The Bulldog Splitfin is probably extirpated from all these basins except for the ríos Duero and Sahuayo infrabasins. All these drainages are/were populated with fish from the ESU Alpro1:

Maximum Extent of Occurence of Alloophorus robustus:

Status :

International Union for Conservation of Nature (IUCN): not assessed (assessment in process)

Conservation status and population trends of Mexican Goodeids (Lyons, 2011): vulnerable/declining.: "Once known from over 50 different localities, this species now persists at about 25. Since the 1990s, it has disappeared from Lake Chapala and the adjacent Santiago and Lerma rivers, from the Laja River, a major Lerma tributary, and from Lake Yuriria. The species has become rare in the Lake Cuitzeo/Grande de Morelia, Lake Pátzcuaro and Lake Zirahuén basins, persisting only in spring areas and small tributaries (Lyons et al., 1998; Soto-Galera et al., 1998, 1999; Mercado-Silva et al., 2006; Domínguez-Domínguez et al., 2008). Losses have been from a combination of declines in water quality and quantity (e.g., Chapala, Cuitzeo) and predation and competition from introduced non-native species (e.g., variable platyfishXiphophorus variatus (Poeciliidae) in the Laja River; largemouth black bassMicropterus salmoides (Centrarchide) in Lake Zirahuén). Remaining strongholds include the La Mintzita Springs in the Lake Cuitzeo basin near the city of Morelia, Lake Zacapu in the headwaters of the Angulo River drainage, a Lerma River tributary, and the Duero River drainage, also a Lerma River tributary, including the La Luz and Orandino spring lakes."

Alloophorus robustus inhabits typically quiet waterbodies like lakes, ponds, reservoirs and slowly flowing rivers and streams. It lives over substrates of mud, sand, clay and rocks in depths of 1 to 2m. Different forms of vegetation can be found, including water hyacinths (Eichhornia), water lilies (Nymphaea), club-rush (Scirpus), Ceratophyllum, Potamogeton and green algae, but may be sparse. Brian Kabbes described in 1998 one habitat of this species, the Lago Orandino. He recorded a clear lake with a bit turbidity. Under overhanging plants, he saw Alloophorus waiting for prey. He predicated the species as shy, apparently preferring some current.

Biology:

In May 1904 Meek found 108-120mm long females containing 20-38 young fish, each of them 17-19mm long. Fry of 20-22mm SL in UMMZ collections appeared between 12. May and 12. June. A 19mm fish had been collected on 19. February in a warm (24.5°C) spring and another one of that length was captured on 9. March from Lago de Camécuaro near Zamora. Thus there is the potential for an extended reproductive period. Ovaries with embryos in various stages of development were noted between 5. May and 16. August from the Pátzcuaro lake, but young were born only during a two-month period (April - June, Mendoza, 1962). This suggests there is only one brood cycle. The average of brood size has been 23.7 young per ovary, including only 0.42% runts.

Diet:

This species is characterised by a large mouth and strong jaws. The teeth are sharply conic and it’s got a relatively short intestine. This fish is probably the most highly developed carnivore in the family feeding mainly from other fish (In the gut of one Alloophorus was found a middle-sized Poeciliopsis infans.), big insects and worms. Alloophorus robustus is definitely a predator. Brian Kabbes described the way to hunt similar to that of a pike.

Size:

The maximum known SL is 143mm (Miller et al, 2005).

Colouration:

This species shows many big blotches on its sides (extending onto belly in juveniles), that are fading in large fish. Breeding males show rarely a subterminal black band and a yellow terminal band in its median fins. Bean designated the colour as uniform pale brown with unspotted fins and the opercle with a golden tint. Wischnath meant, "according to the mood the body appears, besides gray brown, more or less dark, including the fins. In a few cases the body exhibits a dark, weakly marked spotting." However, young specimen remind of Chapalichthys pardalis with bigger and rounder spots, covering the sides.

Sexual Dimorphism:

At first appearance, males and females of the Bulldog Splitfin are not very easy to distinguish. The safest characteristic is the Splitfin in males, means the for Goodeinae typical mating organ formed by a notch after the first seven shortened rays of the Anal fin. Additionally, male Alloophorus robustus have a much bigger Dorsal fin than females. As a third character, the shape might mentioned: males are usually shorter and a shade higher than females, but to this character needs a bit experience. Normally, no difference in colouration between the sexes is visible.

Remarks:

The Bulldog Splitfin is the largest Goodeid species besides Goodea atripinnis, reaching (following some authors) 170mm. Like many other predatory fish, live food, mainly fish, crayfish, big insects and worms, seem to be necessary for a successful breeding in captivity.

Riehl (pers. comm., Hieronimus) documented a phenotypical female of 150mm SL with testes and first beginnings of a Splitfin.

Though this species is widely distributed, it is not very common. On several surveys of the GWG, the participants were able to find only few specimens: A juvenile inidividual in the Cuitzeo lake, directly in dense reed (2014), three specimens in the Molino Viejo de Chapultepec spring system on two surveys (2014, 2016), also out of dense vegetation, a group of fry in dense root mesh of trees in the La Luz spring (2016) and several adults and juveniles at the same place with seine nets in 2018.

Husbandry:

Looking on the biotopes of Alloophorus robustus, they suggest the species may prefer a habitat with none to moderate current, structured with rocks, roots and areas with dense submerse vegetation. Intraspecific or against other fish of similar size, little aggession can be observed, nevertheless, the tank set up should feature areas where the fish can hide as this is part of the species' behaviour. Fry is eaten in almost all of the cases, and this seems to happen even when the quantity and quality of food is maximised and the number of places for the fry to hide is numerous. When separate brought up fry with a size of 4 or 5cm is added to the group, it usually works properly to bring them up with the adults. It is probably not possible to get a flock breeding colony.

The recommended tank size is at least 250 liters, bigger tanks with a generous base and little height (25cm are enough) are better for sure. A bit with roots and/or rocks structured tanks with dense submerse vegetation in the corners and bigger free areas to swim seem to do best with this species. The current should be low to moderate, neverteheless the oxygene level should be quite high (at least 8mg/l).

In the wild, adults of this species feed from bigger invertebrates, shrimps, crayfish, tadpoles, worms, but mainly from small to middle sized fish, so feeding with similar food, means small fish, earthworms, Gammarids, shrimps and other middle sized food from animalistic sources will be best for this predatory fish. In aquarium, it additionally feeds well from flake food, granulate and even tablets, additionally freeze dried food like Brine Shrimps is eaten greedy, but the species needs live or contentful frozen food to spawn and breed. According to its nature as an ambush predator hiding in vegetation, and in contrast to its size, this species is a bit shy.

Concerning water quality, this species is in need of bigger water changes (60-80% every week) like most of the Goodeids, especially as a predatory species that concentrates waste materials quicker in the surrounding water than fish using other food sources. Therefore an automatic water changing system can be helpful. Otherwise, in combination with constant temperatures higher than 24°C, fish may get sick, lose resistance against diseases and age too fast. So for keeping the strain healthy and strong, give the fish a rest during winter time with temperatures lower than 20°C for 2 or 3 months so they stop producing fry. In spring, when the temperature slowly increases, they will start spawning at 20 or 21°C and won't stop until it gets colder again or when it gets too warm (25°C).

This species does very well when is kept in the open from spring to fall, starting when the water temperature by day exceeds 17°C and cold periods are no longer expected. Bring them out in the early afternoon, the time of the day with the highest water temperature. During the warm summer, reproduction will stop and may occur again in fall. Bring the fish in before the water temperature deceeds 17°C by day and keep them cool for the first days, then slowly raise the temperature but try to stay below 20°C over the winter time.